1. Field of Invention
The present invention relates to an antenna coil structure and fabricated method therefor and more particularly, to a radio frequency identification (RFID) antenna coil with flexible substrate, higher inductance and a fabricated method therefor.
2. Related Art
Nowadays, non-contact radio frequency systems have been generally applied in many industries. In the future, after each product leaves the factory, a non-contact radio frequency system will be attached on the product. This system will record relative data about upstream and downstream manufacturers of the product (such as product specification, material, and shipping data), data required by logistics (such as logistics network and stock information), information required by consumers (such as price, qualified mark, instruction manual, and service station). And different clients have different access rights to the information.
The structure of the radio frequency identification (RFID) antenna coil system may be divided into two parts: the first part is a card module, comprising: a power supply and an antenna coil for transmitting and receiving data, a transceiver module, and an identification data; the second part is a reader device, comprising: a transceiver antenna coil, a transceiver module, and a control circuit. The reader device transmits an electromagnetic wave, and when the card module approaches the reader device, the antenna coil in the card module will receive the electromagnetic wave, and store the energy as an electric power for the card module, and transmit the identification date in the card module to the reader device as a radio wave, for confirmation and further control.
To enhance the inductive coupling efficiency, usually the number of turns of coil windings is increased to enhance inductance. However, many problems may be caused with the fabricated method, such as, enlarged element volume, increased resistance value, multi-circle signal noise, reduced induction distance, and weaker recognition rate.
Referring to Japanese Patent No. JP2002368525, wherein the antenna coil is processed with a multi-layer lamination and a magnetic powder substrate (e.g. Mg, Fe, Co etc.) perpendicular to the antenna coil is disposed at a central part of the antenna coil, thereby increasing the inductance, such a method can increase the inductance, however, the element thickness is increased, and also the antenna is inflexible, and therefore, the method has no essential advantage and competitiveness in market application.
Referring to Japanese Patent No. JP2000261230, the fabrication of an antenna coil is similar to the above one in that multi-layers of antenna are laminated, and the difference there-between is in that here the magnetic substance is arranged in a same direction with the metal wiring. The element thickness can be reduced; however, the inductance can thus only be raised in a limited range.
Therefore, it becomes one of the problems to be solved by the researchers how to provide a RFID antenna coil and fabricated method therefor, for enabling the antenna coil to be flexibility and have higher inductance.